The invention relates to an evaporated fuel discharge preventing apparatus.
As an apparatus for preventing an evaporated fuel from being discharged into an atmospheric air by providing an evaporated fuel adsorbing element in an air cleaner portion for adsorbing and collecting the evaporated fuel evaporated from an internal combustion engine or the like at a time when the internal combustion engine stops, there has been conventionally provided a structure as shown in FIG. 7, in which an air cleaner case 102 is provided on an upper portion of an air cleaner chamber 101 communicating with an intake manifold and a blow-by gas introduction pipe (these elements are not illustrated), and a cylindrical evaporated fuel adsorbing element 103 and a cylindrical air cleaner element 104 are provided within the air cleaner case 102 in such a manner that respective axes extend in a vertical direction and the former is arranged on a lower side of the latter, thereby adsorbing and collecting the evaporated fuel generated at a time when the internal combustion engine stops by the evaporated fuel adsorbing element 103, and purging the evaporated fuel adsorbed and collected in the evaporated fuel adsorbing element 103 in accordance with the atmospheric air stream as shown by arrows A in FIG. 7 generated by an intake negative pressure at a time when the engine is driven. This structure is disclosed, for example, in JP-U-61-183456 and JP-U-61-194761. This is set to a first prior art.
Further, as shown in FIG. 8, there has been provided a structure in which an air cleaner main body 201 is disposed laterally, a filter 202 and an adsorbent 203 are arranged in series within the air cleaner main body, and a passage 204 is provided on an outer peripheral portion of the adsorbent 203, adsorbing and collecting the evaporated fuel by the adsorbent 203 at a time when the engine stops and flowing the atmospheric air within the adsorbent 203 as arrows B in FIG. 9 at a time when the engine is driven so as to purge the evaporated fuel collected within the adsorbent 203. This structure is disclosed, for example, in JP-U-58-113861. This is set to a second prior art.
In this case, the element 103 and the adsorbent 203 adsorbing the evaporated fuel as mentioned above are structured such that an amount of transmitting air is less than an amount of transmitting air of the air cleaner elements 104 and 202 in order to prevent the evaporated fuel adsorbed and collected in the element 103 and the adsorbent 203 from being purged at a large amount for a short time at a time when the engine is driven.
Accordingly, in the first prior art mentioned above, since a part of the air sucked at a time when the engine is driven passes through the evaporated fuel adsorbing element 103 having a little amount of transmitting air, an airflow resistance is increased and there is a risk that a performance of the internal combustion engine is reduced.
Further, in the second prior art mentioned above, since most of the sucked air passes through the adsorbent 203, there is also a risk that a performance of the internal combustion engine is reduced in the same manner as that of the first prior art.
Accordingly, an object of the present invention is to provide an evaporated fuel discharge preventing apparatus which can sufficiently adsorb and collect an evaporated fuel without causing a reduction of engine performance as mentioned above.
In order to solve the problems mentioned above, in accordance with the present invention, there is provided an evaporated fuel discharge preventing apparatus comprising:
an evaporated fuel generating portion;
an air cleaner element; and
an adsorbing device arranged in a passage between the evaporated fuel generating portion and the air cleaner element,
wherein the adsorbing device is formed by an intake air passage portion laterally formed within the device so as to pass through and communicated with the passage at both ends, an adsorbent layer arranged on an outer periphery of the intake air passage portion, and a member covering an outer surface in a non-ventilating state except a side of the intake air passage portion in the adsorbent layer, and an inner diameter of the intake air passage portion of the adsorbing device is set to be substantially equal to or more than an inner diameter of the intake air passage.
In accordance with the present invention, the evaporated fuel and the blow-by gas (hereinafter, both thereof are also referred to as evaporated fuel) generated within the intake air passage or the evaporated fuel flowing out from an atmospheric port of a canister or the like, at a time when the engine stops, slowly flows within the intake air passage portion laterally disposed in the adsorbing device. Accordingly, the evaporated fuel is adsorbed and collected by the adsorbent layer arranged on the outer periphery of the intake air passage portion.
When the engine is driven, an ambient air flows from the side of the air cleaner through the intake air passage portion in the adsorbing device so as to be supplied to the engine via the intake air passage and the canister. At this time, the evaporated fuel adsorbed and collected in the adsorbent layer in the adsorbing device is sucked to the air (the ambient air) flowing through the intake air passage portion in the adsorbing device and purged to the engine together with the air.
Further, since the intake air flows within the intake air passage portion without flowing through the adsorbent layer, and an inner diameter of the intake air passage portion in the adsorbing device is set to be substantially equal to or more than an inner diameter of the front and rear passages, an intake air resistance is significantly small in the adsorbing device portion with respect to the air flowing within the passage. Accordingly, an engine performance is not reduced by the intake air resistance.
Further, in the present invention, the adsorbent layer may be provided only on a substantially lower half portion of the outer periphery of the intake air passage portion.
Since the intake air passage portion of the adsorbing device is arranged laterally, the evaporated fuel slowly flowing in a lateral direction on the side of the lower portion in the intake air passage portion at a time when the engine stops is mainly adsorbed and collected to the adsorbent layer on the lower side of the intake air passage portion.
Accordingly, as mentioned above, even in the case that the adsorbent layer is provided only on the substantially lower half portion of the outer periphery in the intake air passage portion, it is possible to sufficiently adsorb and collect the evaporated fuel. Further, it is possible to reduce a cost in comparison with the structure in which the adsorbent layer is provided in all around the periphery, by omitting the adsorbent layer on the upper half portion.
Further, in the present invention, a thickness of the adsorbent layer in a direction perpendicular to an axis of the intake air passage portion on the side of the lower portion may be large while that on the side of the upper portion may be small.
Accordingly, since the evaporated fuel is mainly adsorbed and collected on the side of the lower portion of the adsorbent layer, it is possible to increase an adsorbing and collecting capacity of the evaporated fuel by increasing the thickness on the side of the lower portion. Further, since the adsorbent layer is also provided on the side of the upper portion of the adsorbing passage portion, the evaporated fuel is adsorbed and collected even in the adsorbent layer on the side of the upper portion. Accordingly, the evaporated fuel can be further efficiently adsorbed and collected.
Furthermore, in the present invention, a filter may be provided between the intake air passage portion and the adsorbent layer, and the filter may be bent in a wave shape.
With the structure, a surface area on the side of the intake air passage portion in the adsorbent layer becomes larger than that of a flat filter, whereby it is possible to increase an adsorbing efficiency of the evaporated fuel.